The principle of multilateralism, the bedrock of international climate diplomacy, is facing unprecedented strain as populism and geopolitical conflict rise. This fragile state of global cooperation was laid bare at the Cop30 UN climate summit in Belém, Brazil, last November, where negotiations teetered on the brink of collapse. While a deal was ultimately struck, it satisfied few and underscored the immense challenges ahead in a world where the United States, under Donald Trump, explicitly rejects collaborative solutions.
The Belém Deal and the Shadow of US Unilateralism
The outcome of the Cop30 summit was a classic, unsatisfying compromise. The Belém agreement was too weak to ensure the necessary cuts in greenhouse gas emissions and relegated the critical discussion on roadmaps to phase out fossil fuels to a voluntary side agreement. However, the fact that any deal was reached at all was seen by some as a minor victory, proving that nations can still find slivers of common ground even amid dire and dangerous geopolitics.
The most ominous cloud over the proceedings, however, was the absence of the United States. President Trump began the process of withdrawing from the Paris Agreement in January 2025 and sent no official delegation to Cop30. Delegates were acutely aware that his influence could be felt from afar. This fear was rooted in a shocking precedent set at an International Maritime Organisation (IMO) meeting in October. There, US officials reportedly used aggressive tactics—including threats of visa revocations and trade sanctions—to oppose a new carbon levy on shipping, a move described by Australian billionaire Andrew Forrest as "thuggery." The IMO talks broke down, delaying the levy for a year.
New EU Tariffs and the Coalition of the Willing
Further testing the limits of multilateralism is the European Union's pioneering Carbon Border Adjustment Mechanism (CBAM), which comes into force this month. This 'green tariff' will penalise high-carbon imports like steel from countries with lax emission controls. The EU argues it encourages cooperation by levelling the playing field and incentivising other nations to strengthen their climate policies. "The best CBAM is one you don't have to use," said EU climate chief Wopke Hoekstra.
Yet many developing nations, led by China, view it as a unilateral and unfair trade barrier and attempted to have it censured at Cop30. Alongside these tensions, a 'coalition of the willing' is moving ahead with fossil fuel transition plans outside the full UN process. Over 80 countries at Cop30 failed to secure a binding resolution on phaseout roadmaps but are now pursuing a Plan B. Colombia will host a pivotal conference on the fossil fuel phaseout this April, creating a parallel forum for ambitious nations.
A Precarious Path to Cop31 and Beyond
The resilience of international climate cooperation faces its next major test at Cop31 in Turkey in 2026. Governments must confront the stark reality that their current national emission plans are inadequate and would lead to a catastrophic 2.5C of global heating. The summit itself will be an unusual experiment, taking place in Turkey but largely under Australian control due to a last-minute hybrid presidency deal struck at Cop30.
With 2026 likely to be another record-hot year, reliance on multilateralism may seem like a slender hope. However, the alternative—abandoning the framework for the whims of individual governments, many of them opaque autocracies, and the volatility of capital markets—offers no viable path to averting climate breakdown. A decade after the Paris Agreement, the world's shared future still hinges on that one crucial, embattled principle: cooperation.
